Er:Yag Laser Energy & Frequency Effects On Veneer De-Bonding

This study investigates the de-bonding efficiency and material changes of IPS e.max CAD veneers under different Er:YAG laser settings to optimize clinical laser de-bonding. The study, ethically approved, used 40 maxillary first premolars with uniform enamel. CAD/CAM ceramic blocks (3 × 3 mm²) were tested for de-bonding strength, and 10 × 10 mm² blocks for translucency and Vickers hardness. Samples were divided by thickness (0.5 mm, 1.0 mm) and laser parameters (E0: control, E1: 300 mJ, 15 Hz, E2: 225 mJ, 20 Hz, E3: 150 mJ, 30 Hz). De-bonding time, pulp temperature change (∆T), fracture modes, shear strength, surface morphology, translucency, and hardness were assessed. Statistical analysis included ANOVA, t-tests, and Pearson correlation for de-bonding time and ∆T. Laser de-bonding at 150 mJ, 30 Hz resulted in longer time and higher heating than 300 mJ, 15 Hz and 225 mJ, 20 Hz, with no difference between the latter two. Thicker veneers (1.0 mm) showed longer time and higher heating than thinner ones (0.5 mm), with a strong correlation between time and ∆T (R²=0.739). Laser treatment had no significant effect on re-bonding strength, morphology, translucency, or hardness. At 4.5 W, 1.0 mm veneers should use 300 mJ, 15 Hz or 225 mJ, 20 Hz for de-bonding, while 0.5 mm veneers should use 225 mJ, 20 Hz. Laser de-bonding has no significant effect on re-bonding strength, surface morphology, translucency, or hardness.